AMBER Archive (2002)

Subject: Re: SHAKE troubles

From: Stéphane Teletchéa (steletch_at_biomedicale.univ-paris5.fr)
Date: Wed May 29 2002 - 05:50:12 CDT

Le Mercredi 29 Mai 2002 12:07, Arvid Soederhaell a écrit :
> Dear all,
> I have some problems with SHAKE that I do not understand. I get the error
> message
>
> COORDINATE RESETTING CANNOT BE ACCOMPLISHED,
> DEVIATION IS TOO LARGE
> NITER, NIT, LL, I AND J ARE : 0 0 1963 3195 3196
>
> no matter what i do???!!! The error message comes from the shake.f
> subprogram. The message implyes that i take a too long timestep, but even
> a timestep of 0.5 fs is too long! (Normally one should be able to use a 2
> fs timestep.) The simulation is stable if i turn off SHAKE and use a
> 0.2 fs timestep. The temperature in the simulation never exceeds 350 K.
>
> Any suggestions to what could be the problem?
>
> (The system is a DPPC lipid membrane with TIP3 water, and I use amber6)
>
> Arvid

The size of your box may be too small.
You should have about 10 A between your solute and the verges of your box.
Stef